When booted, contemporary personal computers often take approximately twenty seconds to load the operating system before the user can begin working on a task. This long delay annoys users, and sometimes causes users to not bother starting a computer when another means to accomplish the task can be used, thereby limiting the personal computer's usefulness.
To avoid having to boot a computer to use its functionality, various solutions have been introduced, such as having the computer enter a standby state (e.g., an ACPI S3 sleep state) following its prior use. In the standby state, some power is provided to the system memory to retain the memory contents. While standby allows the personal computer to relatively quickly resume to its useful state, standby has the drawback of draining the battery when in the sleep mode, and therefore is not always desirable. The standby mode also loses data if power is lost, which means that even desktops or plugged-in laptops can lose data during a power failure.
Another solution to provide for rapid startup is referred to as hibernate (e.g., an ACPI S4 state), in which the contents of the memory are transferred to a hard disk hibernation file upon hibernation, and read back from the hibernation file upon resuming to the normal operating state. This solution also has drawbacks, including that it takes a relatively long time to resume, as the hibernation file needs to be transferred back from the relatively slow hard disk drive into system memory and unpacked.